April 2, 1920] 



SCIENCE 



351 



drawing a 25 c.c. aliquot and adding it to 100 c.c. 

 of aeetone-ether (2: 1), and titrating with 0.1 N 

 alcoholic KOH solution, using phenolphthalein as 

 indicator. The remainder of the "milk" is incu- 

 bated for 24 hours at 38° C, with occasional rota- 

 tion of the flask, and the titration repeated on 

 another 25 c.c. aliquot. The features of the 

 method are, (1) the use of an artificial "milk" 

 containing no acid producing substances other 

 than the emulsified oil, (2) the determination of 

 the acidity on aliquot portions of the emulsion. 



The mftuence of various antiseptics on the activ- 

 ity of lipase: Lerot S. Palmer. (By title.) The 

 activity of a commercial lipase was tested using the 

 technic described in the previous abstract. 

 Chloroform, iodoform and acetone were found to 

 have a marked retarding influence on the lipase, 

 depending on the concentration of the antiseptic. 

 Very small quantities of mercuric chloride and 

 iodine, each completely paralyzed the lipase ac- 

 tivity. Formaldehyde had no retarding effect up 

 to one part in 250, concentrations between 1: 1,000 

 and 1: 2,000 actually having a noticeable accelera- 

 ting effect on the lipase activity. 



The activity of phytase as determined by the 

 specific conductivity : F. A. Collatz and C. H. 

 Bailey. (By title.) The hydrolytic cleavage of 

 phytin by phytase results, in the appearance of 

 salts of phosphoric acid in the digestion mixture. 

 The electrical conductivity of the latter is thereby 

 increased, and may be employed as a measure of 

 the progress of the reaction. To a water solution 

 of phytin was added crude phytase prepared from 

 wheat bran, and several such preparations were 

 incubated at temperatures differing by 5° inter- 

 vals from 25° to 60°. The electrical conductivity 

 was measured every 15 minutes until it ceased to 

 change materially. The rate of hydrolysis was 

 accelerated by increased temperatures up to 55°, 

 which appeared to be the optimum for this enzyme. 

 Plotting the data, calculated to conductance at 30° 

 in order to compensate for increased mobility of 

 the ions at higher temperature, the curves have 

 different shapes at each temperature. As the tem- 

 perature increases to the optimum, the increase in 

 conductivity per unit of time is more rapid at the 

 outset, but also reaches approximate equilibrium 

 more promptly. 



The fermentation of fructose by a group of pen- 

 tose-fermenting bacteria: W. H. Peterson, E. B. 

 Fred and A. Davenport. In the fermentation of 

 fructose by these organisms acetic and lactic acids 

 are the chief end products. Coincident with the 



production of these acids is the formation of 

 mannitol to the extent of about 20-30 per cent, of 

 the fructose. The mannitol thus formed can be 

 fermented to acetic and lactic acids by the same 

 bacteria that produced it. It is suggested that the 

 fructose first breaks down into acetic and malic 

 acids and the latter then undergoes decarboxylation 

 yielding lactic acid. Evidence for regarding malic 

 acid as an intermediate product is the fermenta- 

 tion of malic acid to lactic acid. The strong re- 

 ducing conditions set up in the breaking down of 

 fructose into acetic and malic acid probably brings 

 about the reduction of another portion of the 

 fructose to mannitol. 



Factors influencing the invertase activity of mold 

 spores in sugar: Nicholas Kopeloff and S. 

 Btall. (By title.) The invertase activity of the 

 spores of Aspergillus S. Bainier, Aspergillus niger 

 and Penicillium expansum is exhibited at concen- 

 trations of sugar varying from 10 to 70 per cent. 

 It has also been found that the maximum inver- 

 tase activity of these mold spores occurs between 

 50 and 60 per cent, concentrations. It was noted 

 that an increase in the number of mold spores is 

 responsible for increased invertase activity in a 

 saturated sugar solution. However, the least num- 

 ber of spores per c.c. of Penicillium expansum and 

 Aspergillus niger required to produce inversion in 

 saturated sugar solution is between 50,000 and 

 110,000. About 5,000 spores of Aspergillus S. 

 Bainier are needed to cause inversion. The evi- 

 dence that mold spores alone are capable of deteri- 

 orating cane sugar is corroborated by the data 

 herein presented. 



Carbon nitrogen ratio in relation to plant meta- 

 bolism: A. M. GuRJAR. (By title.) The supply of 

 nitrogen determines the relative proportion of car- 

 bohydrates and proteins in the tomato plant. 

 Changes in these proportions are accompanied by 

 very marked changes in the metabolism of the 

 plant, as follows: (a) Although the C: N ratio 

 may be as high as 19 and as low as 2, the fruiting 

 takes place only between the ratios 4 and 6. (6) 

 respiration varies directly as the value of C: N 

 ratio, (c) Photosynthesis varies inversely as the 

 value of C: N ratio. {d) In nitrogen starved 

 plants, eatalase activity is not parallel to respira- 

 tion, but varies inversely with it. (e) Under etio- 

 lation, the high carbohydrate plants are reduced to 

 protoplasmic respiration sooner than the low car- 

 bohydrate plant, which means that the enzyme 

 system of the former fails to make available the 

 starch reserve. (/) The high carbohydrate plants 



